Freezing Yeast - Home Brew Forums
Register Now For Free!

Home Brew Forums > Home Brewing Beer > Fermentation & Yeast > Freezing Yeast

Reply
 
Thread Tools
Old 12-08-2010, 07:24 AM   #1
logos
Recipes 
 
Dec 2010
detroit, MI
Posts: 2


Typically freezing something living kills it. The reason is that ice crystals break the cell walls that are critical for life.

Back in undergrad, I did quite a bit of research in a biochem lab. We didn't work with yeast, but we did use quite a lot of E. coli containing various genes we wanted to express as proteins. In the lab, you often need to store bacteria for long periods of time as a way of storing bits of DNA sequence or a plasmid you want to use again.

I figured that the method we used to store bacteria was probably applicable to the storage of yeast.

The way we did it was to first concentrate the cells by centrifuging. Then we would re-suspend the cells in a solution of buffer (neutral pH salt solution) and glycerol. We could then store the cells at -80 degrees centigrade for several years.

I tried a similar approach to storing yeast for home brewing. I kept about 10ml of a conical tube of White Labs California Ale yeast, using the remainder for a pale ale. To the remainder I added some sugar water boiled with a few teaspoons of chicken broth (yeast nutrient would be better, I just wanted to supply some nitrogenous compounds, amino acids that are not present in sugar water). I let it sit for a couple days on the counter. I released the pressure in the tube and added about 20% glycerol (eyeballed it). You can get glycerol at almost any pharmacy. Threw the tube the in freezer (just a regular freezer, about -20 degrees C).

Now about two months later, I pulled the tube out and grew up a starter with some extra LME. The yeast grew up well. I put in the fridge to precipitate as much of the yeast as possible out of solution, decanted the supernatant, and then pitched it into my ESB wort. 24 hours later, I have strong air lock activity.

Just an interesting alternative way of preserving microorganisms that I hadn't previously seen mentioned here. Fairly simple to do. Glycerol protects the yeast cells from freezing temperatures by preventing ice crystal formation. The tube stays liquid the entire time.

 
Reply With Quote
Old 12-08-2010, 07:41 AM   #2
DeafSmith
HBT_LIFETIMESUPPORTER.png
 
DeafSmith's Avatar
Recipes 
 
Jan 2009
Richardson, TX
Posts: 1,448
Liked 34 Times on 32 Posts


Sounds like an easy way to store yeast.

You didn't say anything about sterilizing the glycerol, so I assume that's not necessary - i.e., bugs can't live in glycerol?

I have a frost free freezer which sometimes cycles up to near freezing to defrost. Maybe I could sandwich the yeast tube between a couple of gel packs to keep it cold during the defrost cycle.

 
Reply With Quote
Old 12-08-2010, 01:28 PM   #3
bja
Recipes 
 
Nov 2007
Pittsburgh, Butler
Posts: 2,061
Liked 168 Times on 126 Posts


There are several threads here about freezing yeast with glycerine and sterile water.

What's the purpose of the sugar water and chicken broth?

I've had very good luck using slants. I just propagated a 1-1/2 year old slant of wlp001 with no problems at all.
__________________
____________________________________________

I know it just wouldn't be right to kill all the stupid people that we meet, but do you think it would be appropriate to just remove all of the warning labels and let nature take its course?

 
Reply With Quote
Reply
Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
First time freezing yeast...is this normal? Clifton Fermentation & Yeast 20 12-08-2010 12:59 AM
lab grade glycerol safe for freezing yeast? bovineblitz Fermentation & Yeast 4 10-15-2010 02:45 PM
Freezing yeast in mason jars? Hilbert Fermentation & Yeast 6 07-13-2010 05:56 PM
Freezing yeast question starrfish Fermentation & Yeast 1 04-13-2010 05:06 PM
Yeast bank vials not freezing? c0bra Fermentation & Yeast 4 08-20-2009 08:18 PM


Forum Jump